The historic handshake planned between the Queen and Martin McGuinness is to take place behind closed doors, it has emerged.

The Northern Ireland Deputy First Minister will attend a cross-border event in Belfast on Wednesday, which Irish President Michael D Higgins will also attend.

But the initial meeting and handshake between the Queen and the senior Sinn Fein representative is expected to take place in a private room at the beginning of the engagement, sources close to the planning have said.

The meeting is nevertheless being seen as a major milestone in efforts to normalise relations between nationalists and unionists.

Sinn Fein president Gerry Adams confirmed that his party's ruling executive had backed the planned meeting, but he added: "This will understandably cause difficulties for some republicans and nationalists, especially for those folks who suffered at the hands of British forces."

The leading peace charity Co-operation Ireland is to host the event for the Queen and Mr Higgins to celebrate the arts and culture across the island at Belfast's Lyric Theatre on Wednesday. It is understood the meeting will take place without cameras being present, before the Queen, Mr McGuinness and other key guests including Mr Higgins and Northern Ireland First Minister Peter Robinson join the main event, which will be covered by the media.

Sinn Fein's ruling council, the ard comhairle, met for four hours in Dublin before announcing its decision to accept the invitation made to Mr McGuinness. Mr Adams said Sinn Fein wanted to see a new republic in which the traditions of orange and green could be brought together in a cordial union. The ard comhairle decision was not unanimous but was a clear majority, the party confirmed.

There has been speculation since the Queen's momentous visit to the Republic of Ireland in May last year that a senior Sinn Fein figure would meet her during the two-day trip planned for Northern Ireland next week to mark the Diamond Jubilee. Mr McGuinness, a former IRA commander, was always the candidate to shake the Queen's hand but delicate talks have been going on for months to arrange a suitable venue and occasion. Sinn Fein has stressed the meeting is not a celebration of the Jubilee.

Mr Adams said of the party's decision: "We don't have to do it. We're doing it because it's the right thing to do, despite the fact that it will cause difficulties for our own folk. But it's good for Ireland. It's good for this process we're trying to develop. It's the right time and the right reason. After Martin McGuinness completes this engagement he will be as true, as staunch, as active a republican as he ever was."

Mr Robinson said he was glad the Deputy First Minister had accepted the invitation. "We recognise that this will be a difficult ask for Her Majesty the Queen and a significant step for republicans," he said. "The process has required us all to reach out and take decisions outside our comfort zone. It is the right decision and a step forward for Northern Ireland."